2007 Silverado 2500 new style

I'm getting P0446 code - EVAP vent system. Sometimes after 1,000km sometimes after one day. Any suggestions how to fix it?? Thanks, Danigo

 

P0446 Evaporative Emission Control System Incorrect Purge Flow

This is it................

 

Circuit/System Description

This DTC tests the evaporative emission (EVAP) system for a restricted or blocked EVAP vent path that would cause excess amounts of vacuum to be developed in the EVAP system. With the purge valve open and the canister vent valve open, if EVAP system vacuum goes above a calibrated threshold, the test will fail.

Conditions for Running the DTC



DTCs P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0120, P0121, P0122, P0123, P0128, P0220, P0222, P0223, P0443, P0449, P0452, P0453, P0502, P0503 are not set.
The ignition voltage is between 11-18 volts.
The barometric pressure (BARO) is more than 74 kPa.
The fuel level is between 15-85 percent.
The start-up engine coolant temperature (ECT) is less than 35°C (95°F).
The start-up intake air temperature (IAT) is between 4-30°C (39-86°F).
The start-up ECT and IAT are within 8°C (14.4°F) of each other.
The purge solenoid valve is enabled.
DTC P0446 runs once per trip when the above conditions have been met.
Conditions for Setting the DTC



The FTP sensor is more than 12 inches H2O vacuum for 5 seconds. OR
The FTP is less than -2.5 inches H2O or more than +5 inches H2O for 60 seconds after a cold start.
Action Taken When the DTC Sets

DTC P0446 is a Type B DTC.

Conditions for Clearing the MIL/DTC

DTC P0446 is a Type B DTC.

Diagnostic Aids



An intermittent condition could be caused by a damaged EVAP vent housing, a temporary blockage at the EVAP canister vent solenoid valve inlet, or a pinched vent hose. A blockage in the vent system will also cause a poor fuel fill problem.
An EVAP canister that is restricted can cause this DTC to set.

 

Thanks a lot for the answer. I'll check it out. D.